Naloxone vs Naltrexone: Understanding the Key Differences

Introduction

Opioid Use Disorder (OUD) is characterized by a dependence on opioids. It affects nearly 2.1 million people in the U.S. and more than 16 million people worldwide. It is a chronic condition, which can also lead to fatalities.

OUDs, while severe, can be managed. Some treatment options for OUDs are Naloxone and Naltrexone. In this blog, we shall be considering their key differences, their efficacy in terms of opioid treatment, and how well they can prevent opioid overdose.

What is Naloxone?

Naloxone is an opioid antagonist. As an opioid antagonist, it binds tightly to the opioid receptors in the brain and blocks the effects of other opioids. In that, it reduces the “high” or “euphoric” feeling that opioids generally give rise to. 

Naloxone is especially useful in emergency situations, where there is a suspected opioid overdose. It has been used in cases where heroin, oxycodone, or fentanyl overdoses are suspected, as it reverses the effects of the same. The good thing is one does not have to be a healthcare professional to administer Naloxone in these situations, it is available as a shot or even a nasal spray which can be administered by anybody. 

Naloxone is a fast-acting medicine and can save lives. Therefore, it is always necessary to keep Naloxone around in cases of opioid use.

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What is Naltrexone?

Naltrexone is an opioid antagonist and works by blocking the high or pleasurable feelings that come with taking opioids. By reducing the effects, it reduces the cravings and hence is used in treating OUDs. 

Naltrexone is a prescription medication and comes as tablets or shots. Some familiar brand names are Revia (tablet) and Vivitrol (injection).  Naltrexone is taken daily, weekly, or monthly, as prescribed by the doctor. The good thing about Naltrexone is that it is not habit-forming or addictive.

Naloxone vs Naltrexone: Key Differences

When comparing Naloxone vs Naltrexone, what needs to be kept in mind is that they are both opioid antagonists. They work by blocking the effects of opioids and are used with OUDs. However, in different ways.

Naloxone is a fast-acting medication and is used to reverse the effects of an opioid overdose. The World Health Organization reports that out of the 600,000 deaths related to overdose in a year, more than 25% of these deaths are opioid overdose deaths. Therefore, Naloxone can be a life-saving medication and it is very easy to use that anyone can administer it. 

Naltrexone, meanwhile, is a prescription medication that is used in the treatment of OUDs. It is also used in the treatment of alcohol use disorder. It blocks the effects of opioids, but it is not used in emergency situations as it is not that fast-acting. It is used for long-term treatment and is a daily or monthly medication.

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Effectiveness in Different Situations

The main difference when considering Naltrexone vs Naloxone, is their effectiveness in different situations. Now, Naltrexone is used in the treatment of substance use disorders, especially OUDs and alcohol use disorder. It blocks the effects of opioids and alcohol in that people do not feel the same pleasurable feelings they get with using the substance. 

With opioids and alcohol, they increase dopamine levels in the brain and also opioid levels. With Naltrexone, what it does is, it lowers the levels of dopamine and opioids and blocks the effects of these substances. By doing so, it reduces cravings. One can still experience withdrawal symptoms with Naltrexone, however, it depends on the type of medication as well as the dosage. Therefore, medical supervision is required while using Naltrexone. 

On the other hand, unlike other OUD treatment medications like methadone or buprenorphine, Naltrexone is not habit-forming. It is not addictive either. So, there is very little potential for misuse. 

Now, coming to Naloxone, it works differently than Naltrexone despite being an opioid antagonist. It works by reversing the effects of opioids, hence, it is very useful in emergency conditions like opioid overdose. Naloxone is available as shots and nasal sprays, and anybody can administer it. One small move with Naloxone can save lives. In fact, as per the 2023 article, “Naloxone has been hailed as life-saving. Why isn’t it given to those who need it?”, there has been a 14% decrease in opioid-related deaths after Naloxone was made more accessible. 

On the other hand, Naloxone is an emergency medication and cannot be used in long-term treatment of OUDs, as it is a short-term opioid blocker. Moreover, it must also be kept in mind that Naloxone is only an emergency medication and not a cure. So, medical assistance will still be needed even after it is used in cases of opioid overdose.

Side Effects: Naloxone vs Naltrexone

When it comes to comparing Naloxone vs Naltrexone in terms of side effects, both have general side effects like:

• Vomiting
• Body aches
• Dizziness
• Diarrhea

Naloxone and Naltrexone come with some severe side effects, too. For instance, Naloxone can lead to withdrawal symptoms as it reverses the effects of opioids. Moreover, among people with heart conditions, it can strain the heart. However, these effects are nowhere as dangerous as opioid overdose itself. 

Meanwhile, Naltrexone can lead to:

• Depressed mood
• Suicidal ideation
• Lowered tolerance to opioids
• Liver problems
• Anaphylaxis or severe allergic reactions, which require immediate attention.

Who Should Use Naloxone vs. Naltrexone?

Naloxone is a short-acting opioid blocker. It works by blocking the effects of opioid's, and is very useful in reversing the effects of an opioid overdose. It must be administered as soon as any signs of opioid overdose are observed, which include:

• Shallowed breathing or absent breathing
• Pinpoint pupils
• Bluing of the lips and/or nose
• Loss of consciousness

It is available as shots or a nasal spray. It can be administered by anyone. While it can lead to withdrawal symptoms and increase the pressure on the heart among people with pre-existing heart conditions, it is still a life-saving drug. However, medical assistance will still be needed after Naloxone has been administered.

Meanwhile, Naltrexone is a prescription-only medication. It is used in the treatment of substance use disorders like OUDs and alcohol use disorder. It blocks the effects of these substances and reduces cravings for the same. It can be given as a pill or a long-acting injection. It is used in combination with psychotherapy for lasting recovery and sobriety.

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How Are Naloxone And Naltrexone Dosed?

Naloxone is available as shots and nasal sprays. When an opioid overdose is suspected, it must be administered immediately. It is a fast-acting drug, and usually, effects are seen within 3 minutes. Otherwise, a second dose can be administered. Its effects last only for 30-90 minutes, hence, the person will need medical assistance and must be taken to the nearest emergency room immediately. 

Naltrexone, meanwhile, is available in the form of tablets and injections. Tablets are usually 50 mg and are prescribed one per day, however, the doctor can generally begin by prescribing 25 mg per day. Meanwhile, Naltrexone injection is long-acting, and each vial contains 380mg. Hence, it is administered once in 4 weeks or once in a month. Naltrexone is a prescription-only medication, so it must be consumed/taken only as prescribed by the doctor.

Frequently Asked Questions

What is another name for naltrexone?

Naltrexone is known by its brand names like Revia (tablet), Depade (tablet), and Vivitrol (injection).

What is the difference between naloxone and Narcan?

Narcan is the brand name for Naloxone, which was first given when it was approved to reverse opioid overdose. 

What is the difference between naltrexone and naltrexone hydrochloride?

Naltrexone is an opioid antagonist while naltrexone hydrochloride is the hydrochloride salt of naltrexone. It is relatively purer and long-acting as well.